510 research outputs found
The Road Ahead for Networking: A Survey on ICN-IP Coexistence Solutions
In recent years, the current Internet has experienced an unexpected paradigm
shift in the usage model, which has pushed researchers towards the design of
the Information-Centric Networking (ICN) paradigm as a possible replacement of
the existing architecture. Even though both Academia and Industry have
investigated the feasibility and effectiveness of ICN, achieving the complete
replacement of the Internet Protocol (IP) is a challenging task.
Some research groups have already addressed the coexistence by designing
their own architectures, but none of those is the final solution to move
towards the future Internet considering the unaltered state of the networking.
To design such architecture, the research community needs now a comprehensive
overview of the existing solutions that have so far addressed the coexistence.
The purpose of this paper is to reach this goal by providing the first
comprehensive survey and classification of the coexistence architectures
according to their features (i.e., deployment approach, deployment scenarios,
addressed coexistence requirements and architecture or technology used) and
evaluation parameters (i.e., challenges emerging during the deployment and the
runtime behaviour of an architecture). We believe that this paper will finally
fill the gap required for moving towards the design of the final coexistence
architecture.Comment: 23 pages, 16 figures, 3 table
R&D Proposal Development of Micro-Pattern Gas Detector Technologies
Development of advanced gas-avalanche detector technologies and associated electronic-readout systems for applications in basic and applied researc
Impedance Control Network Resonant dc-dc Converter for Wide-Range High-Efficiency Operation
This paper introduces a new resonant converter architecture that utilizes multiple inverters and a lossless impedance control network (ICN) to maintain zero voltage switching (ZVS) and near zero current switching (ZCS) across wide operating ranges. Hence, the ICN converter is able to operate at fixed frequency and maintain high efficiency across wide ranges in input and output voltages and output power. The ICN converter architecture enables increase in switching frequency (hence reducing size and mass) while achieving very high efficiency. Three prototype 200 W, 500 kHz ICN resonant converters, one with low-Q, one with medium-Q and one with high-Q resonant tanks, designed to operate over an input voltage range of 25 V to 40 V and an output voltage range of 250 V to 400 V are built and tested. The low-Q prototype ICN converter achieves a peak efficiency of 97.1%, maintains greater than 96.4% full power efficiency at 250 V output voltage across the nearly 2:1 input voltage range, and maintains full power efficiency above 95% across its full input and output voltage range. It also maintains efficiency above 94.6% over a 10:1 output power range across its full input and output voltage range owing to the use of burst-mode control.National Science Foundation (U.S.) (Award 1307699
Optimal False-Positive-Free Bloom Filter Design for Scalable Multicast Forwarding
Large-scale information dissemination in multicast communications has been increasingly attracting attention, be it through uptake in new services or through recent research efforts. In these the core issues are supporting increased forwarding speed, avoiding state in the forwarding elements and scaling in terms of the multicast tree size. This paper addresses all these challenges – which are crucial for any scalable multicast scheme to be successful – by revisiting the idea of in-packet Bloom filters and source routing. As opposed to the traditional in-packet Bloom filter concept, we build our Bloom filter by enclosing limited information about the structure of the tree. Analytical investigation is conducted and approximation formulae are provided for optimal length Bloom filters, in which we got rid of typical Bloom filter illnesses such as false-positive forwarding. These filters can be used in several multicast implementations, which is demonstrated through a prototype. Thorough simulations are conducted to demonstrate the scalability of the proposed Bloom filters compared to its counterparts
ICedge: When Edge Computing Meets Information-Centric Networking
In today’s era of explosion of Internet of Things (IoT) and end-user devices and their data volume, emanating at the network’s edge, the network should be more in-tune with meeting the needs of these demanding edge computing applications. To this end, we design and prototype Information-Centric edge (ICedge), a general-purpose networking framework that streamlines service invocation and improves reuse of redundant computation at the edge. ICedge runs on top of Named-Data Networking, a realization of the Information-Centric Networking vision, and handles the “low-level” network communication on behalf of applications. ICedge features a fully distributed design that: (i) enables users to get seamlessly on-boarded onto an edge network, (ii) delivers application invoked tasks to edge nodes for execution in a timely manner, and (iii) offers naming abstractions and network-based mechanisms to enable (partial or full) reuse of the results of already executed tasks among users, which we call “compute reuse”, resulting in lower task completion times and efficient use of edge computing resources. Our simulation and testbed deployment results demonstrate that ICedge can achieve up to 50× lower task completion times leveraging its networkbased compute reuse mechanism compared to cases, where reuse is not available
Software Defined Networks based Smart Grid Communication: A Comprehensive Survey
The current power grid is no longer a feasible solution due to
ever-increasing user demand of electricity, old infrastructure, and reliability
issues and thus require transformation to a better grid a.k.a., smart grid
(SG). The key features that distinguish SG from the conventional electrical
power grid are its capability to perform two-way communication, demand side
management, and real time pricing. Despite all these advantages that SG will
bring, there are certain issues which are specific to SG communication system.
For instance, network management of current SG systems is complex, time
consuming, and done manually. Moreover, SG communication (SGC) system is built
on different vendor specific devices and protocols. Therefore, the current SG
systems are not protocol independent, thus leading to interoperability issue.
Software defined network (SDN) has been proposed to monitor and manage the
communication networks globally. This article serves as a comprehensive survey
on SDN-based SGC. In this article, we first discuss taxonomy of advantages of
SDNbased SGC.We then discuss SDN-based SGC architectures, along with case
studies. Our article provides an in-depth discussion on routing schemes for
SDN-based SGC. We also provide detailed survey of security and privacy schemes
applied to SDN-based SGC. We furthermore present challenges, open issues, and
future research directions related to SDN-based SGC.Comment: Accepte
Probabilistic structural mechanics research for parallel processing computers
Aerospace structures and spacecraft are a complex assemblage of structural components that are subjected to a variety of complex, cyclic, and transient loading conditions. Significant modeling uncertainties are present in these structures, in addition to the inherent randomness of material properties and loads. To properly account for these uncertainties in evaluating and assessing the reliability of these components and structures, probabilistic structural mechanics (PSM) procedures must be used. Much research has focused on basic theory development and the development of approximate analytic solution methods in random vibrations and structural reliability. Practical application of PSM methods was hampered by their computationally intense nature. Solution of PSM problems requires repeated analyses of structures that are often large, and exhibit nonlinear and/or dynamic response behavior. These methods are all inherently parallel and ideally suited to implementation on parallel processing computers. New hardware architectures and innovative control software and solution methodologies are needed to make solution of large scale PSM problems practical
POWER AND PERFORMANCE STUDIES OF THE EXPLICIT MULTI-THREADING (XMT) ARCHITECTURE
Power and thermal constraints gained critical importance in the design of microprocessors over the past decade. Chipmakers failed to keep power at bay while sustaining the performance growth of serial computers at the rate expected by consumers. As an alternative, they turned to fitting an increasing number of simpler cores on a single die. While this is a step forward for relaxing the constraints, the issue of power is far from resolved and it is joined by new challenges which we explain next.
As we move into the era of many-cores, processors consisting of 100s, even 1000s of cores, single-task parallelism is the natural path for building faster general-purpose computers. Alas, the introduction of parallelism to the mainstream general-purpose domain brings another long elusive problem to focus: ease of parallel programming. The result is the dual challenge where power efficiency and ease-of-programming are vital for the prevalence of up and coming many-core architectures.
The observations above led to the lead goal of this dissertation: a first order validation of the claim that even under power/thermal constraints, ease-of-programming and competitive performance need not be conflicting objectives for a massively-parallel general-purpose processor. As our platform, we choose the eXplicit Multi-Threading (XMT) many-core architecture for fine grained parallel programs developed at the University of Maryland. We hope that our findings will be a trailblazer for future commercial products.
XMT scales up to thousand or more lightweight cores and aims at improving single task execution time while making the task for the programmer as easy as possible. Performance advantages and ease-of-programming of XMT have been shown in a number of publications, including a study that we present in this dissertation. Feasibility of the hardware concept has been exhibited via FPGA and ASIC (per our partial involvement) prototypes.
Our contributions target the study of power and thermal envelopes of an envisioned 1024-core XMT chip (XMT1024) under programs that exist in popular parallel benchmark suites. First, we compare XMT against an area and power equivalent commercial high-end many-core GPU. We demonstrate that XMT can provide an average speedup of 8.8x in irregular parallel programs that are common and important in general purpose computing. Even under the worst-case power estimation assumptions for XMT, average speedup is only reduced by half. We further this study by experimentally evaluating the performance advantages of Dynamic Thermal Management (DTM), when applied to XMT1024. DTM techniques are frequently used in current single and multi-core processors, however until now their effects on single-tasked many-cores have not been examined in detail. It is our purpose to explore how existing techniques can be tailored for XMT to improve performance. Performance improvements up to 46% over a generic global management technique has been demonstrated. The insights we provide can guide designers of other similar many-core architectures.
A significant infrastructure contribution of this dissertation is a highly configurable cycle-accurate simulator, XMTSim. To our knowledge, XMTSim is currently the only publicly-available shared-memory many-core simulator with extensive capabilities for estimating power and temperature, as well as evaluating dynamic power and thermal management algorithms. As a major component of the XMT programming toolchain, it is not only used as the infrastructure in this work but also contributed to other publications and dissertations
Clustering Arabic Tweets for Sentiment Analysis
The focus of this study is to evaluate the impact of linguistic preprocessing and similarity functions for clustering Arabic Twitter tweets. The experiments apply an optimized version of the standard K-Means algorithm to assign tweets into positive and negative categories. The results show that root-based stemming has a significant advantage over light stemming in all settings. The Averaged Kullback-Leibler Divergence similarity function clearly outperforms the Cosine, Pearson Correlation, Jaccard Coefficient and Euclidean functions. The combination of the Averaged Kullback-Leibler Divergence and root-based stemming achieved the highest purity of 0.764 while the second-best purity was 0.719. These results are of importance as it is contrary to normal-sized documents where, in many information retrieval applications, light stemming performs better than root-based stemming and the Cosine function is commonly used
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